Magnesium Ferrite Research Articles

Synthesized MgFe<sub>2</sub>O<sub>4</sub> nanoparticles to remove Pb<sup>2+</sup> from aqueous solution

In the present paper, nanosized magnesium ferrite (MgFe2O4) material is synthesized by the hydrothermal method. The size and microstructure of magnesium ferrite were analyzed based on X-ray diffraction (XRD), scanning electron microscopy (SEM). The nitrogen adsorption-desorption was used for determination of surface area (Brunauer – Emmett – Teller (BET)) and porosity of the fabricated material. The adsorption behavior of Pb2+ using a new magnetic adsorbent is investigated. The adsorption characteristic and Pb2+ removal efficiency of the adsorbent have been determined by investigating the influence of operating variables such as dosage of manganese ferrite. The maximum Pb2+ sorption capacity was found to be 16,08 (mg/g) and obtained using 0,1 g/L MgFe2O4 when pH equals 5, a temperature of 25 °C, and contact time as 24 h. The Langmuir and Freundlich models were used to fit the experimental data and these showed good correlations.

Structural and Magnetic Behavior of MFe<sub>2</sub>O<sub>4</sub> Nanopowders for Water Treatment

This study describes the sol-gel method's synthesis of ferrites [MFe2O4, M(II) = Co, Cu, Mg, Ni, and Zn]. The structure was studied by X-ray diffraction analysis. The surface morphology was studied using scanning electron microscopy (SEM), and the magnetic properties were studied using Mössbauer spectroscopy. The diffraction peaks at 30.1◦, 35.6◦, 43.2◦, 53.6◦, 57◦, and 62.6◦ can be attributed to Bragg reflections (2 2 0), (3 1 1), (4 0 0), (4 2 2), (5 1 1), and (4 4 0) planes confirm the formation of a cubic spinel structure of ferrite nanocrystals. The average size of magnesium ferrite crystallites calculated from the half-width of the most intense peak (3 1 1) was 25.96 ± 4.32 nm. Magnesium ferrite is a magnetically soft ferromagnetic powder with a predominance of the magnetite phase and relatively high magnetisation values. The magnitude of the hyperfine magnetic field for the studied nanoparticles is in the range of 440-490 kOe, which confirms the hypothesis that the analysed samples are particles of an iron-containing oxide with a disordered structure.

Effect of annealing temperature on structural and electrochemical behaviour on MgFe2O4 as electrode material in neutral aqueous electrolyte for supercapacitors

Binary metal oxides possess unique structures and multiple oxidation states, making them highly valuable in electrochemical analysis. This study aims to determine the effect of annealing temperature on the electrochemical properties of magnesium ferrite when used as an electrode material in a neutral aqueous electrolyte. We utilized the sol–gel technique to synthesize the material and annealed it at various temperatures. Our analysis of the material using different characterization techniques reveals significant changes in its structural and electrochemical properties. We found that the material exhibited a range of phases, and higher annealing temperatures led to improved electrochemical properties. The electrochemical measurements showed reversible and redox pseudo-capacitance behavior, with the material annealed at 500 °C exhibiting the highest specific capacitance of 117 F g−1 at a current density of 0.5 A g−1. Capacitive and diffusion-controlled processes govern the total charge storage mechanism, and their contribution changes significantly as the annealing temperature varies. The capacitance retention of 500 °C annealed sample was 58% and it remained stable. This work establishes a correlation between annealing temperature on structural, morphological, and electrochemical behavior, thereby opening up avenues for tailoring them effectively. These findings can be useful in the development of future electrode materials for electrochemical applications.

Morphology dependent negative dielectric permittivity in spinel ferrite nanostructures

Metamaterials with negative dielectric permittivity has become a research hotspot due to their potential efficacy in various electromagnetic utilizations, such as, filter and antenna design, novel capacitance and inductor design, electromagnetic absorber etc. This study unfurls immense possibilities of inducing metamaterial properties such as negative dielectric permittivity in Magnesium Ferrite, a naturally occurring compound, just by restructuring the morphology. Herein, we report the correlation between structural, dielectric, and magnetic properties of the system in the same chemical composition but different morphologies, namely, nano solid spheres (NSSs) and nano hollow spheres (NHSs). Strikingly, only NHSs show negative dielectric permittivity owing to the Lorentz dielectric resonance in the vicinity of a metamagnetic transition. Further investigations show that the hollow cores and greater number of interfaces in NHSs, in comparison to NSSs, cause the uncompensated charges to accumulate within them and release at some frequencies and temperatures, leading to the backscattering of dipoles, which in turn induces the resonance. NSSs with stronger anti-ferromagnetic interaction and impermeable morphology do not show any sign of negative dielectric permittivity.

Investigation of Visible and UV Light‐Induced Photocatalysis Properties of Oleic Acid‐Ligated Cobalt‐Mixed Magnesium Ferrite Nanoparticles for Photodegradation of Cationic and Anionic Dyes

Owing to numerous potential applications in multiple fields, the study of nanosized magnetic spinel ferrites has been gaining significance. Synthesis and characterization of high‐quality magnetic nanocrystals with narrow size distribution, enhanced magnetic saturation, and outstanding properties for bioenvironmental applications are presented in the current study. Nanoparticles of oleic acid‐ligated Co0.5‐mixed Mg0.5Fe2O4 were prepared by a simple thermal decomposition method. The effect of cobalt (Co2+) content on the structural, optical, magnetic, and thermal properties of magnesium ferrite was assessed by powder X‐ray diffraction (PXRD), Fourier transform infrared spectroscopy (FT‐IR), and vibrating sample magnetometer (VSM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). High‐resolution transmission electron microscopy (HR‐TEM) and energy dispersive X‐ray (EDX) spectroscopy were used to determine morphology and composition, respectively. Nanoparticles produced are highly crystalline and homogeneous, having an average size of 10 nm, with large saturation magnetization (61 emu/g) and high magnetic moment. Photocatalytic properties of prepared nanocrystals were studied by degradation of anionic Orange II and cationic methylene blue (MB) dyes under UV and visible light radiations for different time intervals. The anionic Orange II dye exhibited higher degradation, up to 97.2% and 92.2%, within a 90‐minute time period of ultraviolet and visible light irradiation, respectively. The cationic MB dye also displayed significant degradation, up to 91.9% and 93.8%, within 300 min under UV and visible light sources, respectively. The synthesized OA‐ligated nanoparticles degrade cationic and anionic dyes more effectively than previously reported in the literature and, thus, can be prime candidates for effective photo catalytic dye degradation and waste water cleaning applications, through the harvesting of ambient solar energy.

Research on influence of grinding blast furnace return ore on reduction swelling index of low silicon fluxed pellets and production practice

Pellet quality is one of the key technologies restricting the smelting of high proportion pellets in the blast furnace, especially the reduction swelling index of low silicon fluxed pellets. In this paper, the inhibition effect of grinding blast furnace return ore on the reduction swelling index of low silicon fluxed pellets was studied and application has been conducted in Shougang Jingtang Company. The experimental results show that the addition of 5–15% fine grinding blast furnace ore into pellet production significantly reduced the reduction swelling index of pellets from 23.5% to 14.3%. Microstructure and energy spectrum analysis shows that calcium ferrite, magnesium ferrite and liquid phase in the pellets with fine grinding blast furnace return ore increased obviously with a more uniform distributed liquid phase between hematite particles than in the basic group pellets and tended to be “homogenized”. It is conducive to inhibiting the generation of ferric whiskers in the reduction process of the hematite phase, and thus contributes to the reduction of the swelling index. Since its implementation at Shougang Jingtang in 2020, this technology has yielded positive results. The fluxed pellets exhibit good quality with an alkalinity of 1.1, a SiO2 content of 2.1%, and a reduction in the swelling index from 18.1% to 16.5%. Besides, the pellet ratio into blast furnace has reached 55%, the cumulative average utilization coefficient of three 5500 m3 super-large blast furnaces is 2.43t/(m3. d), and the monthly average for a single furnace reaches 2.62t/(m3. d). Meanwhile, consumption reduction of calcium-containing flux slaked lime in fluxed pellets by 0.9% is greatly beneficial to reducing the cost of pellets and expanding the resources of pellet powder.

Sintered magnesium ferrite particles in decolorization of anthraquinone dye AV 109: Combination of adsorption and fenton process

Magnesium ferrite (MgFe2O4) particles were synthetized by sol-gel method and used in the decolorization of the Acid Violet 109 (anthraquinone dye, AV109) water solutions' by combination of adsorption and heterogeneous Fenton process. The material's morphology and elemental analysis of the surface were revealed by Scanning electron microscopy and Energy Dispersive Spectroscopy (SEM/EDS). The X-Ray Diffraction (XRD) technique was used to analyze the crystallographic phase. In the first part of the decolorization experiment, the adsorption ability of the synthesized particles was investigated. During the adsorption study influence of pH was investigated. In the second part of the decolorization experiment, the effects of the various parameters on the Fenton process were studied such as the initial concentrations of hydrogen peroxide, dye, and magnesium ferrite particles. Influence of magnesium ferrite particles structure, pH value and reaction temperature were also investigated. The decolorization reaction was followed by UV-Visible (UV-Vis) spectrophotometry. At optimal conditions, the dye decolorization was 99.1% (55.4% by adsorption and 43.7% by the Fenton process). Both the adsorption and the Fenton process obey second-order kinetics.

Phase transitions and spectral shifts: a quantum mechanical exploration of vibrational frequency in magnesium ferrite.

Spinel ferrites represent an integral subset of magnetic materials, with their inherent properties largely influenced by cation occupancy and spin interaction. In this study, we present an in-depth theoretical exploration of the phase transition landscape of pure magnesium-ferrite, deploying hybrid functionals and a local Gaussian basis set to scrutinize the relaxed lattice structure, relative energy, magnetic properties, electronic characteristics, and vibrational frequencies. Our investigation reveals that the ground state of magnesium-ferrite is an open-shell system with an inverse structure. This is characterized by the complete occupancy of octahedral sites by magnesium atoms, with Iron atoms dispersed between both tetrahedral and octahedral sites. We found a relative energy difference of 0.41 eV between the antiferromagnetic ground configuration and the ferro arrangement within the inverse structure. Furthermore, our research also delved into the impact of spin rearrangement and inversion (X = 0.0, 0.5 and 1) on Raman and infrared spectra. Notably, the lattice distortion from the cubic form, apparent in the optimized structure, resonates in the IR and Raman spectra, resulting in significant splitting. The frequencies calculated in this study align well with experimental values, suggesting that the literature's current assignments warrant reevaluation in light of this new data. The results presented herein can be instrumental in detecting the phase of Mg ferrites from experimental spectra, thereby paving the way for a more profound comprehension of their properties and possible uses.

Sintered magnesium ferrite particles in decolorization of anthraquinone dye AV109: Combination of adsorption and fenton process

Magnesium ferrite (MgFe2O4) particles were synthetized by sol-gel method and used in the decolorization of the Acid Violet 109 (anthraquinone dye, AV109) water solutions' by combination of adsorption and heterogeneous Fenton process. The material's morphology and elemental analysis of the surface were revealed by Scanning electron microscopy and Energy Dispersive Spectroscopy (SEM/EDS). The X-Ray Diffraction (XRD) technique was used to analyze the crystallographic phase. In the first part of the decolorization experiment, the adsorption ability of the synthesized particles was investigated. During the adsorption study influence of pH was investigated. In the second part of the decolorization experiment, the effects of the various parameters on the Fenton process were studied such as the initial concentrations of hydrogen peroxide, dye, and magnesium ferrite particles. Influence of magnesium ferrite particles structure, pH value and reaction temperature were also investigated. The decolorization reaction was followed by UV-Visible (UV-Vis) spectrophotometry. At optimal conditions, the dye decolorization was 99.1% (55.4% by adsorption and 43.7% by the Fenton process). Both the adsorption and the Fenton process obey second-order kinetics.

Structural characterization, optical, and magnetic properties of MgTbxFe2−xO4 nano ferrite particles using a combustion technique

The citrate gel auto-combustion method was utilised to synthesis terbium-doped nanoparticles (NP) with considerable concentrations of magnesium ferrites, using the chemical formula MgTbxFe2−xO4 and an X range of 0.000 to 0.0030 (with an X step of 0.0005). At 300 K, X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transition electron microscopy (TEM), and magnetic characteristics were all determined. The XRD and TEM images indicate nanoscale ranges as well as the cubic spinel structure, which is merely phased, and confirm the normal crystallite size. The lattice parameter and volume decrease as density increases with doping of terbium. The images from the FESEM. It is evident that the grain clusters were found within the material. In the specimen's case, the highly interacting grains were found. The fourier-transformed infrared spectroscopy (FTIR) data clearly suggests that two metallic bands have formed, confirming the cubic spinel ferrites. There are two primary absorption bands visible between 200 and 650 cm−1. The UV–vis investigation demonstrates that the calculated direct band gap energy values have a violet shift. The band gab energy was reported in the range of 415.30 eV to 375.12 eV.The magnetic properties of the hysteresis loops indicate a transition from hard magnetic moments to soft magnetic moments. All magnetic properties were reduced when the Tb3+ ion was substituted. They are excellent for switching memory storage devices as well as telecommunications.

Hybrid calcium magnesium ferrite: A multifaceted nanomaterial for energy, sensing, and environmental applications

The current work employs the urea aided conventional sol–gel procedure to synthesize hybrid calcium magnesium ferrite (CMF – CaO/MgFe2O4) nanomaterial. To verify the existence of synthesized nanomaterials, X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and UV diffuse reflectance spectroscopy (UV-DRS) are employed. The observed crystalline size of the nanomaterials is 44.14 nm. The estimated band gap is 2.36 eV, which is validated using UV-DRS equipment. The investigation's findings are supported by actual applications in electrochemical studies and photocatalytic degradation of synthesized hybrid CMF. It was also investigated how to modify the working electrode's surface to detect heavy metals, drugs, and biomolecules like uric acid, paracetamol, creatinine, cadmium and mercury. Electrochemical research was done to determine the ideal properties of CMF as an electrode material for use in batteries, supercapacitors, and sensors applications. Furthermore, synthesized hybrid CMF exhibits excellent photocatalytic activity, employed as a catalyst to decolorize acid red 88(AR-88) dyes at room temperature under visible light illumination, with a 120-minute photocatalytic activity with the degradation efficiencyof 60.40 %.

Fabrication and characterization of ternary composite MgFe2O4/MoO3@CNTs for the enhanced photocatalytic activity to degrade organic pollutants

The recent industrial revolution and population growth have escalated the threat to the environment. Industries themselves discharge millions of tons of different harmful solvents, chemicals, and organic/metal ions into the water system each year. For the degradation of these organic wastes, photocatalysis has been extensively studied. The most researched classes of nanoparticles used as photocatalysts in environmental remediation are metal oxide and metal ferrite nanostructures. In this context, we have fabricated magnesium ferrite (MgFe2O4) nanoparticles and molybdenum trioxide (MoO3) nanorods by coprecipitation and hydrothermal processes, respectively. Moreover, their binary composite (MgFe2O4/ MoO3) was fabricated to improve the absorption of light in the visible region. Further, its ternary composite was fabricated with CNTs (MgFe2O4/MoO3 @CNT) to enhance photocatalytic activity by reducing the recombination rate via trapping photoinduced species. X-rays diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopic analysis were carried out for structural confirmation. From XRD data, the crystallite size and other crystallographic parameters of the fabricated samples were determined. The calculated crystallite sizes of MgFe2O4 and MoO3were 12.74 nm and 31.36 nm, respectively. Band gap calculation and optical studies were done by UV–visible spectroscopy. The decrease in band gap value of MgFe2O4/MoO3 leads to remarkable photocatalytic activity than bare photocatalysts. The photocatalytic performance of all photocatalysts was examined by degrading methyl orange (MO) dye, pendimethalin (PDM), and benzoic acid (BA). Comparative studies revealed that MgFe2O4/MoO3 @CNT exhibited brilliant photocatalytic activity among the aforementioned photocatalysts. It degraded 96%, 82%, and 67% methyl orange (MO), pendimethalin (PDM), and benzoic acid (BA), respectively. This outstanding increase in photodegradation process was due to the movement of photoexcited species from the conduction band to CNTs, where it traps the photoexcited species and limits their chances of recombination. Overall, this research offers a fresh understanding of the effective utilization of the MgFe2O4/MoO3 @CNT ternary composite as a high-performance photocatalyst to address environmental protection concerns when exposed to visible light.

Special features of the structure of modifier of periclase­spinel materials with an increased thermal shock resistance

The main requirement for periclase­spinel refractories during their operation is the ability to multiple thermal cycling, which can lead to thermal absorption of stress in the refractory system. Therefore, resistance to thermal shocks is considered one of the key properties of the material for extending the service life of linings based on them. The structure of the modifier, which is included in the composition of periclase spinel materials, was investigated using X­ray phase and electron microscopic studies, and the influence of its structural features on the performance characteristics of the refractory was substantiated. The structural and phase features of the modifier were revealed, namely, polyphasic and the presence of metastable phases in the composition of the material, which is due to the presence of impurities and their easy ability to form orthosilicates and crystallize during cooling of the fired sample of the modifier, as well as the oxidizing gaseous firing medium due to the partial transition FeO → Fe2O3 with the formation of a pseudobrookite phase and magnesium ferrite, have a positive effect on the heat resistance of the modified periclase spinel material due to the branching of thermodynamic paths of structural and phase changes in the composition of the refractory in the heating—cooling cycles.

A comparative study of green and chemical approaches for photocatalytic activity of novel hybrid bismuth magnesium ferrites (BiMgFe2O4) nanoparticles for Acid Red-88 dye degradation

Uncontrolled release of several dangerous pollutants had negatively impacted the environment causing water pollution and retarded plant growth. Recently, nanoferrites utilized as photocatalyst to eliminate water pollutants. The benefitsofhybrid photocatalyst have significantly improved separating and charge transfer capabilities. In the present investigation novel bismuth magnesium ferrites (BMF - BiMgFe2O4) are synthesized via conventional solution combustion method using green and chemical approach. The particles are confirmed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Scanning electron microscopy (SEM),Energy disperse X-ray diffraction analysis (EDX), UV-DRS (UV diffuse reflectance spectroscopy). The observed crystalline size for the nanoparticles synthesized by green and chemical approach is 25.15 nm and 18.55 nm respectively. Analyzed band gap observed is 2.89 eV and 1.98 eV for green and chemical approach that are confirmed by employing UV-DRS technique. The outcomes obtained from studies are verified with capable applications in photocatalytic degradation. The application of BiMgFe2O4 as catalyst for decolourisation of acid red 88 (AR-88) dyes under visible irradiation at room temperature exhibits superior photocatalytic activity for BiMgFe2O4 is 74.22 % and 85.27 % using green and chemical approach for 120 min respectively. It's significant that the environmental impact of the whole procedure has been assessed with regard to the development of green gramplants utilizing the treated wastewater exhibiting effective plant growth. The overall feasibility of the research presented here provides the opportunity to apply chemically synthesized BMF acts as superior photocatalyst for pollutants from particles in practical applications related to wastewater treatment and other applications in daily life. Using degradedwater yields productive plant growth.

Biosynthesis, characterization, magnetic hyperthermia, and in vitro toxicity evaluation of quercetin-loaded magnetoliposome lipid bilayer hybrid system on MCF-7 breast cancer

Novel biocompatible and effective hyperthermia (HT) treatment materials for breast cancer therapeutic have recently attracting researchers, because of their effective ablation of cancer cells and negligible damage to healthy cells. Magnetoliposome (MLs) have numerous possibilities for utilize in cancer treatment, including smart drug delivery (SDD) mediated through alternating magnetic fields (AMF). In this work, magnesium ferrite (MgFe2O4) encapsulated with liposomes lipid bilayer (MLs), Quercetin (Q)-loaded MgFe2O4@Liposomes (Q-MLs) nano-hybrid system were successfully synthesized for magnetic hyperthermia (MHT) and SDD applications. The hybrid system was well-investigated by different techniques using X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FT-IR), Energy dispersive X-ray (EDX), Vibrating sample magnetometer (VSM), Transmission electron microscope (TEM), and Zeta Potential (ZP). The characterization results confirmed the improving quercetin-loading on the MLs surface. TEM analysis indicated the synthesized MgFe2O4, MLs, and Q-MLs were spherical with an average size of 23.7, 35.5, and 329.5 nm, respectively. The VSM results revealed that the MgFe2O4 exhibit excellent and effective saturation magnetization (MS) (40.5 emu/g). Quercetin drug loading and entrapment efficiency were found to be equal to 2.1 ± 0.1% and 42.3 ± 2.2%, respectively. The in-vitro Q release from Q-loaded MLs was found 40.2% at pH 5.1 and 69.87% at pH 7.4, verifying the Q-loading pH sensitivity. The MLs and Q-MLs hybrid system as MHT agents exhibit specific absorption rate (SAR) values of 197 and 205 W/g, correspondingly. Furthermore, the Q-MLs cytotoxicity was studied on the MCF-7 breast cancer cell line, and the obtained data demonstrated that the Q-MLs have a high cytotoxicity effect compared to MLs and free Q.

Facile synthesis of flower shaped magnesium ferrite (MgFe2O4) impregnated mesoporous ordered silica foam and application for arsenic removal from water

Magnesium ferrite (MF0.33) impregnated flower-shaped mesoporous ordered silica foam (MOSF) was successfully synthesized in present study. MOSF was added with precursor solution of MF0.33 during MF0.33 synthesis which soaked the materials and further chemical changes occurred inside the pore. Therefore, no additional synthesis process was required for magnesium ferrite impregnated mesoporous ordered silica foam (MF0.33-MOSF) synthesis. MF0.33-MOSF showed higher morphological properties compared to other magnesium ferrite modified nanomaterials and adsorbed arsenic III [As(III)] and arsenic V [As(V)] 42.80 and 39.73 mg/g respectively. These were higher than those of other Fe-modified adsorbents at pH 7. As MOSF has no adsorption capacity, MF0.33 played key role to adsorb arsenic by MF0.33-MOSF. Data showed that MF0.33-MOSF contain about 2.5 times lower Fe and Mg than pure MF0.33 which was affected the arsenic adsorption capacity by MF0.33-MOSF. Adsorption results best fitted with Freundlich isotherm model. The possible mechanism of arsenic adsorption might be chemisorption by electrostatic attraction and inner or outer-sphere surface complex formation.

Solar photoactive magnesium substituted copper ferrite photocatalysts for Rose Bengal treatment

In the present investigation, we have reported solar photo active, cost effective and magnetically recoverable magnesium substituted copper ferrites successfully prepared by simple co-precipitation method. The prepared materials were characterized for structural and microstructural analysis using PXRD, SEM, EDS, FT-IR and UV–Visible spectroscopy. It was observed that, when copper introduces into magnesium ferrite system light absorption shifted to visible region, this is due to formation of metastable energy levels just below the conduction band of magnesium ferrites. As a result an MgCuFe2O4 catalyst exhibits excellent efficiency under solar light irradiation. These catalysts are stable for longer period even after many runs and magnetically separable. Based on the analysis result these nanomaterials can be used as potential environmental and energy applications under natural sunlight irradiation.

Structural, optical and magnetic properties of MgFe2O4 and Ni0.5Zn0.5Fe2O4

Spinel ferrite nanoparticles Nickel zinc ferrite (Ni1-xZnxFe2O4 (x = 0.5)) and magnesium ferrite (MgFe2O4) are synthesized by sol-gel auto-combustion and annealed at 1150 °C and 1200 °C respectively. X-ray diffraction (XRD) confirms the presence of a single-phase cubic spinel structure. Lattice parameters crystallite size and density of ferrites are calculated from the XRD data. Surface morphology of the spinel ferrites is studied using Field Emission Scanning Electron Microscopy (FE-SEM). Optical properties such as bandgap, refractive index, extinction coefficient, dielectric constant, and dielectric loss are calculated using UV–Visible spectroscopy. Two absorption bands for each are identified by Fourier Transform Infrared Spectroscopy (FT-IR) peaks, with the lower frequency (400Hz) corresponding to the metal-oxide bond vibrations at the octahedral site and the higher frequency (600Hz) corresponding to the metal-oxide bond vibrations at the tetrahedral sites of the spinel lattice. Magnetic properties are analysed using Vibrating Sample Magnetometer.

Dehydrogenation of ethylbenzene to styrene over magnesium-doped hematite catalysts

Styrene is an important building block of the plastics industry being produced by ethylbenzene dehydrogenation. The commercial catalysts have the disadvantages of deactivation by potassium loss and coke deposition, and chromium toxicity. To overcome these drawbacks, a new catalyst was developed by investigating the effect of magnesium on the catalytic properties of hematite in ethylbenzene dehydrogenation. Hematite was detected for all fresh catalysts and magnetite for the spent ones. Magnesium was found as magnesium ferrite and magnesium oxide, depending on the magnesium amount. Magnesium compounds affect the crystal sizes, the amount of defects and the reducibility of iron oxides, the predominance of each one depending on the composition of the solids. These effects caused important differences in activity, selectivity and stability of the catalysts. The catalyst with Mg/Fe = 0.09, consisting of aggregates of hematite, MgO and magnesium ferrite, showed the highest yield, being the most promising for commercial applications.

Characterization of Nano-Structured Magnesium-Aluminum Ferrites Synthesized by Citrate-Gel Auto Combustion Method

An effort is made to find the solution to the new challenges of modification advancements in ferrite technologies. The hypothetical variation in the structural, magnetic, and electrical properties of cubic spinel magnesium aluminum ferrites introduced by the substitution of doping elements has been rationalized and proven. The outcome of aluminum substitution on the magnesium ferrites has been examined and investigated. Spinel ferrites having compositions of MgAlxFe2-xO4 (x = 0.1, 0.2, 0.3, 0.4) were prepared by the sol-gel auto-combustion method. The prepared sample’s characterization, such as scanning electron microscopy (SEM), DC electrical resistivity, AC electrical resistivity, and dielectric properties measurements, were tested using the respective instruments. The grain size and crystal size of all samples were measured from the micrographs of SEM and XRD Data. It is found that the average grain size is within the range of 300 nm - 550 nm for all different series that are formed, keeping the samples at 1100 °C sintering temperatures. A two-probe method experiment with a temperature range of 30 °C to 500 °C gives data on DC electrical resistivity. The Curie temperature depends on the sintering temperature, and it increases with increasing doping concentration. Also, doping influences grain size, which decreases with increasing concentration. Analyzing the SEM micrographs, it is found that the average grain size must decrease in tendency with increasing Al content. DC electrical resistivity exhibits excellent semiconducting behavior. Frequency dependence, dielectric constant, and dielectric loss factors were measured, keeping the frequency range of 75 Hz to 130 MHz at room temperature. The result shows that the dielectric constant (e) and dielectric loss tangent (tan™) decrease with the increase in frequency, while the AC resistivity and Q-factor increase. Comparing the electrical properties of four compositions, it can be suggested that the mixed ferrite, sample-4 (x = 0.3), shows the highest Q-factor of all at 1100 °C.